ByPan Pylas, AP Business WriterJune 2, 2011

A foreign currency dealer from the Korea Exchange Bank walks past a monitor displaying the Korea Composite Stock Price Index ( KOSPI) and the exchange rate between the South Korean won and US dollar at a dealing room of the bank's headquarters in Seoul April 21, 2011. The KOSPI fell 1.3 percent June 2, 2011, as world stock markets fell sharply on worries about US growth and Greek debt.

LONDON – Stock markets took another battering Thursday on mounting concerns over the state of the U.S. economy, political uncertainty in Japan and a warning that Greece has only a 50-50 chance of avoiding a damaging debt default.

Investor sentiment was jolted by news from the ADP payrolls firm that private employers only added 38,000 jobs during the month. That was far lower than the 175,000 expected in the markets, reinforcing fears that the U.S. economic recovery is quickly running out of steam and that Friday's official government jobs data may come in lower than anticipated.

A weak manufacturing report from the Institute for Supply Management did little to help matters and U.S. stockssuffered one of their worst days in months as investors worried that the U.S. economy was slowing faster than expected.

In Europe, where indexes had already fallen the day before, the FTSE 100 index of leading British shares was down another 0.9 percent at 5,878 while Germany's DAX fell 1.2 percent at 3,918. The CAC-40 in France was 1.2 percent lower at 3,917.

Wall Street was poised for a very modest recovery at the open — Dow futures were up 0.1 percent at 12,286 while the broader Standard & Poor's 500 futures rose a similar rate to 1,314.

At the start of each month, investors have a slew of U.S. economic indicators to digest, in particular the monthly nonfarm payrolls data, which often set the tone in markets for a week or two after their release. Thursday's economic news offering is more modest, with weekly jobless claims likely to take the limelight ahead of Friday's payrolls figures.

The downgrade pushed the country's credit rating deeper into junk status just as Greece is trying to wrap up negotiations for a vital fifth installment of international bailout loans.

Moody's downgraded Greece by three notches from a B1 rating to Caa1 with a negative outlook on Wednesday and said the country's risk of default stood at 50 percent given uncertain growth prospects and increasingly difficult policy challenges.

Despite the constant stream of worries over Greece's debts, the euro has managed to recover somewhat this week, partly on the expectation that the country will get a second bailout to see it through 2013. By late morning London time, it was up 0.6 percent at $1.4430, just shy of its earlier three-week high of $1.4458.

However, with Europe's debt crisis flaring up time and time again — not just in Greece, but in Ireland and Portugal, too — a number of analysts think the currency will soon start to falter.

"The growing likelihood of a default event in Greece and the knock on implications for the other peripheral nations makes us think that the recent healthy rally should be viewed as no more than an opportunity to reduce exposure further to the troubled region," said Simon Derrick, senior currency strategist at Bank of New York Mellon.

Earlier in Asia, much of the attention centered on developments in Tokyo, where the country's Prime Minister Naoto Kan faced a no-confidence motion over his handling of Japan's triple disasters.

Though he won the vote, analysts said his victory could prove short-lived — Kan said he is willing to resign once the country's recovery kicks in.

Kan has been criticized for delays in construction of temporary housing for evacuees from the March 11 disaster, lack of transparency about evacuation information, and a perceived lack of leadership.

Hong Kong's Hang Seng index fell 1.6 percent to 23,253.80, while mainland China's benchmark Shanghai Composite Index sank 1.4 percent to 2,705.18. The Shenzhen Composite Index of China's smaller, second exchange lost 1.5 percent to 1,105.95.In the oil markets, a barrel of crude continued to oscillate in a fairly narrow range above and below $100. Benchmark oil for July delivery was down 46 cents to $99.82 a barrel in electronic trading on the New York Mercantile Exchange.